Agaricus volvatulus Heinem. & Gooss.

Chen, Jie, Parra, Luis A., Kesel, André De, Khalid, Abdul N., Qasim, Tayyaba, Ashraf, Aisha, Bahkali, Ali H., Hyde, Kevin D., Zhao, Ruilin & Callac, Philippe, 2016, Inter- and intra-specific diversity in Agaricus endoxanthus and allied species reveals a new taxon, A. punjabensis, Phytotaxa 252 (1), pp. 1-16 : 10

Agaricus volvatulus Heinem. & Gooss. -Font. in Heinemann, Bull. Jard. Bot. État Brux. 26(1): 61 (1956) Fig. 5

Pileus 8–9 cm diam, at first hemispherical to parabolic, often truncated at the centre, then plano-convex, finally applanate; surface smooth, uniformly covered with innate, radially arranged, dark greyish to dark brownish grey fibrils, with pileus expansion, remaining radially fibrillose or splitting radially or partially cracking into small, appressed, dark brownish grey scales on a white background, with disc staying unbroken, and of a completely dark colour. Margin at first entire and often appendiculate with veil remnants from the annulus, then radially fissile. Lamellae free, crowded, up to 4–5 mm broad, with intercalated lamellulae, whitish at first, then pink, finally dark brown. Stipe 7–10 × 0.4–0.9 cm (1–1.5 cm at base), cylindrical with generally a marginate bulbous base, with numerous rhizomorphs, surface smooth and whitish both above and below the annulus with a strong yellow discolouration on rubbing. Annulus superior, membranous, thick with well delimited margin, up to 1.2 cm broad, upper side smooth, lower side fibrillosewoolly, white. Context white, strongly discolouring chrome yellow on stipe base when cut.

Basidiospores (4.4–)4.5–5.7(–6.2) × (2.6–)2.9–3.2(–3.6) μm, [x = 5.1 × 3.1, Q = 1.45–1.73(–1.9), Qm = 1.62, n = 20], ellipsoid, smooth, brown, thick–walled. Basidia 11–14 × 5.5–6.5 μm, clavate, hyaline, smooth, 4-spored. Cheilocystidia not observed or very rare and isolate. Pleurocystidia absent. Pileipellis a cutis composed of short and very inflated elements of 8–17 μm wide, containing vacuolar pigments in big dark brown vacuoles.

Habitat:—solitary or in clusters on soil, near decomposing plant debris or soil covered with deep litter, in forest,

Specimens examined:— BÉNIN. Atlantique, Niaouli, 8 June 1999, collector André De Kesel , ADK2566 ( BR!) ; TOGO. Plateau Akposso, Béna-Ola, 10 July 2007, collector André De Kesel , ADK4266 ( BR!) ; Imoussa , gallery forest, 13 May 2010, collector L.A. Parra, LAPAF5 (AH!) .

Figures

FIGURE 5. Agaricus volvatulus. a–b. Overall structure (ADK2566). c. Strong yellow discolouration on stipe surface when bruised (ADK4266). d. Marginate bulbous stipe base (LAPAF5). e. Vacuolar pigment in pileipellis hyphae (ADK2566).